(FIA) Annual Inventory Answers the Question: What Is Happening to Pinyon-Juniper Woodlands?

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Forest Inventory and Analysis (FIA) Annual Inventory Answers the Question: What Is Happening to Pinyon-Juniper Woodlands?

John D. Shaw, Brytten E. Steed, and Larry T. DeBlander

Widespread mortality in the pinyon-juniper forest type is associated with several years of drought in Pinus monophylla Torr.&Frem.)—and one the southwestern United States. A complex of drought, insects, and disease is responsible for pinyon or more juniper species (Juniperus spp.); mortality rates approaching 100% in some areas, while other areas have experienced little or no pure stands of pinyon usually are not con- mortality. Implementation of the Forest Inventory and Analysis (FIA) annual inventory in several states sidered a separate type. Pinyon nuts were a coincided with the onset of elevated mortality rates. Adjunct inventories provided supplemental data on staple food for Native Americans of the damaging agents. Preliminary analysis reveals the status and trends of mortality in pinyon-juniper Southwest for thousands of years, and the woodlands. harvest of this valuable resource continues

ABSTRACT today (Lanner 1981). There also are many Keywords: forest inventory, FIA, pinyon pines, pinyon-juniper woodlands, drought, mortality, Ips traditional and modern uses for pinyon and confusus, bark beetles, southwestern United States juniper wood. The extensive range and volume of the resource has generated interest in intensive use, such as an energy-producing biomass crop. However, pinyon-juniper he Forest Inventory and Analysis same systematic sample grid as was used for woodland is seen as a weedy invader of pro- (FIA) is a national USDA Forest periodic inventories, but the plots are evenly ductive grasslands by some. T Service program that conducts for- divided into annual panels that are visited in The Interior West FIA (IW-FIA) pro- est inventory across all land ownerships in a continuous cycle. In western states, one- gram operates in Arizona, Colorado, Idaho, the United States. FIA inventories are based tenth of the plots in a state is sampled per Montana, Nevada, New Mexico, Utah, and on a systematic sample, establishing perma- year, producing a 10-year inventory cycle. Wyoming, which includes most of the range nent sample plots on the ground at an inten- Plots are distributed throughout the state in of the pinyon-juniper type in the United sity of approximately one plot per 6,000 for- each panel. Consequently, annual panels are States. Annual inventory was implemented ested acres. In the past, FIA conducted theoretically free from geographic bias. This in Utah in 2000 and in most of the other periodic inventories in which all plots in a system provides a continuous flow of data, IW-FIA states since then. About the time given state were measured at once. In west- which allows for more flexible analysis op- that annual inventory was started in the IW, ern states it commonly required several years tions and provides opportunities to monitor forest managers and researchers began to no- to measure all the plots in a state. The forest change in ways that were not possible tice an increase in the incidence of insects planned periodic revisitation cycle in the using periodic inventory data. and disease in several forest types, including western United States was 10 years, but ac- Pinyon-juniper woodland is the most pinyon-juniper. Much of the increase has tual cycle lengths sometimes approached 20 common forest type in the American South- been attributed to the drought that spread years. In response to user demand for more west, covering over 36 million acres in 10 across the Southwest beginning in the late timely information, FIA began to test and states and extending into Mexico. The type 1990s (Figure 1). implement an annual inventory system in is defined by the presence of one or more As of Jan. 2005, the drought was ongo- 1996 (Gillespie 1999). pinyon species—usually common and ing and significant drought-related mortal- The annual inventory system uses the singleleaf pinyon (Pinus edulis Engelm. and ity had occurred in the pinyon-juniper type

280 Journal of Forestry • September 2005 mortality. Therefore, the current mortality episode has provided an opportunity to test the usefulness of the FIA annual inventory system for quantifying rapid change in pinyon-juniper woodlands over a large geographic area (Shaw in press). Because of the high degree of interest in the amount of mortality and causal agents, we established an adjunct inventory on a subset of FIA inventory plots to document damaging agents in detail. Here, we describe the extent and severity of mortality in the pinyon-juniper forest type and highlight some of the contributing mortality agents. Drought and Effects on Forests The current Southwest drought began about 1998 (McPhee et al. 2004), but the exact time of onset varies by location and interpretation of climatic data. Although lo- Figure 1. Climate record from 1895 to 2004 for ﬁve southwestern states as recorded in the cally severe, the current drought appears Palmer Drought Severity Index (PDSI). Data points represent the mean annual PDSI for comparable in magnitude to droughts in the National Oceanic and Atmospheric Administration (NOAA) Climate Divisions within each early 1900s, in the 1950s, and during many state (National Climatic Data Center 1994). other dry periods that have been docu- mented using tree-ring–based reconstruc- tions of the past 800 years (Cole et al. 2004, McPhee et al. 2004; Figure 1). In recent months, it appears that some areas affected by drought since the late 1990s are experi- encing a degree of relief (Society of Ameri- can Foresters 2004). Anecdotal reports of drought-related effects on Southwest forests began in 2000, but a dramatic increase in tree mortality occurred in 2002 (Anhold and McMillin 2003). There were local reports of up to 100% mortality of the pinyon component in pinyon-juniper woodland. A rapid expan- sion of high-mortality areas was recorded during aerial surveys between the fall of 2002 and the fall of 2003 (Anhold and Mc- Millin 2003). Although locally severe, little of the observed mortality has been attributed to drought alone. The cause of mortality may be best described as a complex of drought, insects, and disease. Mortality Status and Trends Figure 2. Landscape-scale pinyon mortality in pinyon-juniper woodland in southeastern Data from IW-FIA periodic and annual Utah. (Photo by B. Steed.) inventories offer some insight into the progression of drought-related mortality across (Figure 2). Widespread and locally severe was known to occur. Because the FIA sam- the Southwest. Periodic inventories from mortality has inspired efforts to quantify the ple is unbiased with respect to plot location Arizona, New Mexico, and Utah quantiﬁed effects of drought, insects, and disease over and covers a wide area and extended time predrought conditions of pinyon-juniper the past 5 years. Some of these efforts have period, it provides a unique view of pinyon- forests and more recent annual inventory been local in nature and lack the geographic juniper woodlands. The systematic sample data from Arizona, Colorado, Nevada, and and temporal ranges covered by the FIA pro- also reduces the likelihood of producing er- Utah captured the current drought-related gram. Other efforts provided wider coverage roneous conclusions that may come from mortality episode. Although junipers and but were focused on areas where mortality surveys conducted only in known areas of other species have suffered mortality in some

Journal of Forestry • September 2005 281 areas, FIA plot data suggest that, to date, they are largely unaffected in the pinyon- juniper type. For the sake of simplicity, the figures and trends presented here represent only the pinyon component of the pinyon- juniper type. The IW-FIA program defines a mortality tree as one determined to have died within 5 years of the plot measurement date. Therefore, a distinction between long- standing dead trees and recently killed trees is made in the field. In the case of periodic inventories, this distinction was necessary for the purpose of estimating annual mortality because data were limited to initial plot measurements. In reports based on periodic data, observed mortality is averaged over the 5-year period and reported as annual mortality in the year before inventory. There- fore, using this method it is assumed that 5-year average mortality is representative of the reported year. Periodic inventory data suggest that annual mortality is relatively low for pinyon and juniper species. Based on recent periodic inventory data from Arizona (O’Brien 2002), New Mexico (O’Brien 2003) and Utah (O’Brien 1999), annual mortality, on a volume basis, was estimated at 0.08–0.23% for common pinyon, 0.14% for singleleaf pinyon, 0.01% for oneseed juniper (Juniperus monosperma (Engelm.) Sarg.), 0.01–0.08% for Rocky Mountain juniper (Juniperus scopulorum Sarg.), and 0.01–0.07% for Utah juniper (Juniperus os- teosperma (Torr.) Little). In contrast, e.g., estimates of annual mortality for ponderosa pine (Pinus ponderosa Laws.) ranged from 0.21 to 0.48% in the same inventories. Be- cause these estimates were computed from periodic inventories conducted in relatively normal years (i.e., not excessively droughty), they may be representative of approximate “background” mortality rates. These esti- Figure 3. County-level estimates of pinyon mortality 2000–2004. Mortality values represent mates also include mortality due to fire, so the percentage of mortality of all pinyon trees 5.0 in. DBH and greater (live and mortality), background mortality rates excluding fire on a basal area basis and on plots classified as the pinyon-juniper woodland type and are actually somewhat lower. excludes mortality attributable to fire and logging. Annual inventory was implemented in Basing mortality estimates on a 5-year Utah in 2000, Arizona in 2001, and Colorado in 2002. Data for Nevada are from a pilot average can be advantageous when it is de- inventory conducted in 2004. Annual inventory still has not been implemented in New sirable to smooth year-to-year variation and Mexico. The range of pinyon-juniper woodlands, based on the ranges of common, single- represent a “typical” year. However, the leaf, border, Mexican, and Parry (Pinus quadrifolia Parl.) pinyons, is shown for reference. method also may mask trends that are of Ranges modified using FIA data from digitized maps (USGS 2005). interest or produce biased estimates. For example, consider a periodic inventory that immediately followed a severe fire season. If age would be closer to the true background In the case of insect and disease out- mortality data were attributed only to the mortality rate but still overestimates typical breaks, short-term temporal trends are of previous year, the mortality estimate would mortality because of the inclusion of a severe significant interest. Annual data provide fin- be relatively accurate for that year but would fire year. In addition, it is impossible to er-scale temporal resolution that may reveal drastically overestimate mortality for a typi- discern trends based on a single periodic short-term trends. Preliminary analysis sug- cal year. On the other hand, the 5-year aver- inventory. gests that the progression of drought-related

282 Journal of Forestry • September 2005 which is represented by only a single panel of annual data. However, the Nevada statewide estimate of 2.9% mortality probably is five to 10 times the expected background mortality, based on pinyon mortality rates in other states (O’Brien 1999, O’Brien 2002, O’Brien 2003). Mortality Agents Although mortality has been attributed to drought alone in some cases, the death of a tree is commonly attributable to multiple factors. In conjunction with stress caused by drought, a number of insects and diseases can affect the health of pinyons. These agents may work singly, killing the tree di- rectly, or in concert, with each agent causing cumulative damage or stress that eventually overcomes the tree. Agents of particular im- portance include pinyon ips (Ips confusus Figure 4. Statewide mortality trends in Arizona, Colorado, Nevada, and Utah. Pinyon (LeConte)), twig beetles (Pityophthorus spp. mortality is defined as in Figure 3. Nevada is represented only by 2004 pilot inventory and Pityogenes spp.), pitch moths (families data. Line labeled as “all” represents the combination of all states in which annual data Pyralidae (especially Dioryctria spp.) and were collected in a given year. Sesiidae), black stain root disease (Lep- tographium wageneri (Kendrick) Wingfield), mortality has been captured by annual data served. Thus, the actual “new” mortality for and pinyon dwarf mistletoe (Arceuthobium collected in southwestern states over the past a given year could be estimated by subtract- divaricatum Engelm.). 5 years. ing the cumulative mortality from the previ- The pinyon ips (Figure 5, A and B) is Annual inventory data show that ous year. Compilation methods that can the most important insect mortality agent, drought-related mortality has occurred produce such estimates are under investiga- causing the majority of the pinyon mortality widely across the Southwest. Figure 3 shows tion. in the Intermountain West (Rogers 1993). mortality estimates at the county scale, The similarities and differences in mor- However, ips beetles tend to be only moder- which is a common FIA reporting unit tality rates among states also may be infor- ately aggressive, attacking and killing trees (USDA Forest Service 2005). In the early mative. The fact that the trends shown by stressed by other agents (Hagle et al. 2003). stages of drought (2000–2001), nearly all each of the statewide curves are similar from Outbreaks of this native bark beetle are the mortality occurring at the county scale 2000 to 2003 lends to confidence in the re- known to occur during periods of drought was located in one or two plots in the sults. However, the differences among states (Furniss and Carolin 1977), but also may be county. As the event progressed, mortality revealed by the 2004 data raise a number of associated with root disease, heavy dwarf was recorded on many more plots, but con- questions, perhaps the most important be- mistletoe infection, previous defoliation, siderable variation in the amount of mortal- ing: why? Our preliminary attempts at mod- dense stand conditions, or poor soil condi- ity still occurred among plots within coun- eling mortality risk in the pinyon-juniper tions (McCambridge 1974, Hessburg et al. ties. type suggest that mortality may be predicted 1995, Negron and Wilson 2003, Skelly and When all plots are combined at state or by a combination of edaphic factors and Christopherson 2003). When beetle popu- regional scales, it is evident that the annual stand structural traits. This may allow pre- lations build, outbreaks may continue for a inventory has captured the rapid increase in diction of trends in New Mexico, e.g., where year or two even if stressful conditions, such drought-related mortality across the South- annual inventory still has not been started as drought, are removed. Pinyon ips can west (Figure 4). There are several aspects of but recent periodic inventory data are avail- have two to four generations per season, Figure 4 worth noting. The first is that the able. which has resulted in rapid progression of annual mortality estimates (as well as the Finally, trends revealed by annual data mortality in some areas. county-level estimates in Figure 3) are actu- agree with anecdotal accounts of the pro- Other species of bark beetle may attack ally 5-year cumulative mortality values. gression of mortality. Reports from the field the smaller branches of pinyon pines. These Given the previous explanation of how an- indicated that new insect and disease-caused “twig beetles” are largely from the genera nual mortality is calculated, it would appear mortality declined during 2004 and mortal- Pityophthorus and Pityogenes and are consid- that the data overestimate mortality in a ity, while still increasing, was doing so at a ered secondary beetles that make use of trees given year. However, because data from ear- decreased rate. Inventory data from Utah that are already stressed (Rogers 1993, Cain lier panels show far less mortality than later and Colorado appear to confirm field obser- et al. 1995, Skelly and Christopherson panels, it is possible to infer that the mortal- vations, and data from Arizona suggest a 2003). Some beetles from these genera may ity detected in later years, or at least most of slight decrease in the rate of increase. No attack larger branches and trunks (Cain et al. it, occurred just before the time it was ob- inference of trend is possible for Nevada, 1995, Skelly and Christopherson 2003). Al-

Journal of Forestry • September 2005 283 stain root disease variant L. wageneri var. wagneri is specific to pinyon species. Black stain fungi colonize the water-conducting tissues of the roots and lower stem, prevent- ing movement of water to the foliage. Black- colored bands in the sapwood of roots, the root collar, or lower bole of dying trees (or no more than 6 months dead) indicate infection (Figure 5D). Root-feeding beetles and weevils may spread the fungi as they move to feed and breed. However, the most important method of infection is likely through root contact with adjacent infected trees (Skelly and Christopherson 2003). Infected trees may fade over time but often are killed early by other agents such as pinyon ips (Hessburg et al. 1995, Skelly and Christo- pherson 2003). The disease does not appear to be widespread (Skelly and Christopher- son 2003), although it has been identified in the Four Corners area of southwestern Col- orado and southeastern Utah and is impli- cated in the death of many trees in that area (Dr. Bill Jacobi, Colorado State University, personal communication, 2005). The pinyon dwarf mistletoe (Figure 5E) is a parasitic plant that robs its host tree of water and nutrients. It frequently infects both common and singleleaf pinyons and can appear on other pinyon species within the mistletoe’s distribution (Hawksworth and Wiens 1996, Mathiasen et al. 2002). Infection reduces tree growth and vigor, pre- disposing it to attack by other agents. Several studies (e.g., Negron and Wilson [2003]) suggest that dwarf mistletoe-infected trees are more susceptible to, and perhaps pre- ferred by, pinyon ips. However, dwarf mistletoe alone can kill trees, especially seedlings and saplings. The length of time it takes to Figure 5. Agents associated with mortality of pinyons in drought-affected areas: (A) pinyon kill a tree depends on the level of infection ips beetle, (B) entrance hole and frass from pinyon ips, (C) pitch flow caused by pitch moth, and the age and health of the tree (Hawks- (D) black stain root disease, and (E) pinyon dwarf mistletoe. (Photos by: panel A, T. Eager; worth and Wiens 1996, Mathiasen et al. panel B, University of Arizona; panels C and E, B. Steed; and panel D, W. R. Jacobi.) 2002). Several other insects and diseases can though they usually have little effect on tree the organism(s) responsible for pitch mass- have strong visual effects on pinyon trees but health, these beetles can kill small trees or causing activity on pinyons. Potential agents generally are not important mortality branches of larger trees during periods of include pyralid moth larva (Pyralidae), in- agents. Some areas thought to be mortality drought (Cain et al. 1995) and have been cluding several Dioryctria species, and clear- locations during windshield or aerial surveys associated with occasionally heavy, localized wing moth larvae (Sesiidae) (Cain et al. were, in fact, defoliated by nonlethal agents mortality. Most twig beetle species produce 1995, Skelly and Christopherson 2003, and found to have greened up during subse- two to four generations a year depending on Swift 2004). Injuries inflicted by these spe- quent surveys. However, some of these or- weather and location. cies weaken the host tree, making it suscep- ganisms may predispose trees to attack by Large masses or streamers of pitch (Fig- tible to attacks by other insects (Skelly and other agents. Some of the insects and dis- ure 5C) are indicative of pitch moth activity. Christopherson 2003). If sufficient numbers eases that can be found on pinyons still may The taxonomy and biology of many of these of larvae feed on a tree, the tree may be not be identified. However, the onset of species appear to be poorly understood killed. drought-related mortality has generated new (Swift 2004), resulting in difficulty defining Recent research indicates that the black interest in the ecology of the pinyon-juniper

284 Journal of Forestry • September 2005 woodlands and the taxonomy and general be an important resource for managers and lytidae), in pinõn pine, Pinus edulis. West. N. biology of many associated organisms. researchers. Am. Naturalist 63(4):440–451. O’BRIEN, R.A. 1999. Comprehensive inventory of The Value of Annual Inventory Literature Cited Utah’s forest resources, 1993. Resource Bull. RMRS-RB-1, USDA For. Serv., Rocky ANHOLD, J., AND J. MCMILLIN. 2003. Insect out- The annualized FIA inventory (Gillespie Mountain Res. Sta., Ogden, UT. 105 p. breaks: Bark beetles. 2003 Southwest Drought 1999) was implemented with an associated O’BRIEN, R.A. 2002. Arizona’s forest resources, Summit Report, compilation of the May 12– complement of assumptions and unanswered 1999. Resource Bull. RMRS-RB-2, USDA 13, 2003 meeting in Flagstaff, AZ. Available For. Serv., Rocky Mountain Res. Sta., Ogden, questions. The onset of widespread drought- online at www.mpcer.arizona.edu/megadrought/ UT. 116 p. related mortality in the Southwest is providing drought summit report/science.htm; last O’BRIEN, R.A. 2003. New Mexico’s forest re- an opportunity to test some of the assumptions accessed Dec. 17, 2004. sources, 2000. Resource Bull. RMRS-RB-3, CAIN, R., D. PARKER, AND C. WARD. 1995. Co- and answer some important questions (Shaw USDA For. Serv., Rocky Mountain Res. Sta., in press). In addition, some characteristics of nifer pests in New Mexico. USDA Forest Ser- vice, Albuquerque, NM. 50 p. Ogden, UT. 117 p. this mortality episode have led us to consider ROGERS, T.J. 1993. Insect and disease associates COLE, J., D. GUTZLER,D.MEKO,K.WOLTER, of the pinõn-juniper woodlands. P. 124–125 alternative methods of compilation and analy- AND M. LENART. 2004. Climate experts discuss sis of FIA data. For example, the geographic Southwest drought. P. 2–5 in Southwest cli- in Proc. Managing pinõn-juniper ecosystems for distribution of mortality suggests that geo- mate outlook, September 2004. University of sustainability and social needs. Aldon, E.F., and Arizona Climate Assessment Project for the D.W. Shaw (comps.). Gen. Tech. Rep. RM- graphic delineations not commonly used in 236, USDA For. Serv., Rocky Mountain Res. FIA reporting, such as ecoregional units or dis- Southwest (CLIMAS), Tucson, AZ. Available online at www.ispe.arizona.edu/climas/fore- Sta., Ft. Collins, CO. crete population segments, may better capture casts/swoutlook.htm; last accessed Dec. 17, SHAW, J.D. Drought-related mortality in pinyon- regional variation and reduce variance in sta- 2004. juniper woodlands: A test case for the FIA an- tistical analyses. FURNISS, R.L., AND V.M. CAROLIN. 1977. West- nual inventory system. Proc. of the 6th annual Based on early results, the potential for ern forest insects. Misc. pub. 1339, USDA For- forest inventory and analysis symposium, Denver, CO, Sept. 20–24, 2004. McRoberts, R.E., using annual panels as independent samples est Service, Washington, DC. G.A. Reams, P.C. Van Deusen, and W.H. and time series data appears promising. The GILLESPIE, A.J.R. 1999. Rationale for a national annual forest inventory program. J. For. McWilliams (eds.). Gen. Tech. Rep. WO-xxx, IW-FIA annual inventory system appears 97(12):16–20. USDA Forest Service, Washington, DC (in able to detect trend and magnitude of short- HAGLE, S.K., K.E. GIBSON, AND S.T. TUNNOCK. press). term change during a widespread, patchy 2003. Field guide to diseases and insect pests of SKELLY, J., AND J. CHRISTOPHERSON. 2003. Pin- event such as drought-related mortality. It northern and central Rocky Mountain conifers. yon pine-management guidelines for common also appears that relatively low levels of Forest Health Protection Rep. R1-03-08, pests. University of Nevada Cooperative Exten- sion, Reno, NV. 37 p. change can be detected, at least in cases USDA Forest Service, Missoula, MT. HAWKSWORTH, F.G., AND D. WIENS. 1996. SOCIETY OF AMERICAN FORESTERS. 2004. Western where the variable of interest (in this case, Dwarf mistletoes: Biology, pathology, and sys- US drought outlook improves. P. 1, 5 in The background mortality) is typically at low lev- tematics. Agricultural handbook 709. USDA Forestry Source, Vol. 9, Issue 12, Society of els and relatively constant over time and Forest Service, Washington, DC. 410 p. American Foresters, Bethesda, MD. space. Status and trends probably can be es- HESSBURG, P.F., D.J. GOHEEN, AND R.V. BEGA. SWIFT, C. 2004. Pinõn “pitch mass” borer Dioryc- timated with confidence at larger scales. It 1995. Black stain root disease of conifers. For- tria ponderosae Dyar. Colorado State Univer- sity Cooperative Extension, Fort Collins, CO. may be possible to draw some conclusions at est insect and disease leaflet 145. USDA Forest Service, Washington, DC. Available online at www.coopext.colostat- medium geographic scales, such as the LANNER, R.M. 1981. The pinõn pine: A natural e.edu/TRA/PLANTS/ppitch.html; last ac- county or national forest, but this ability is and cultural history. University of Nevada cessed Jan. 10, 2005. largely dependent on the distribution of the Press, Reno, NV. 224 p. USDA Forest Service. 2005. Forest inventory forest type of interest within the geographic MATHIASEN, R., J.S. BEATTY, AND J. PRONOS. mapmaker. Available online at www.ncrs2.fs. area. For example, in less common forest 2002. Pinyon pine dwarf mistletoe. Forest in- fed.us/4801/fiadb; last accessed Aug. 30, 2005. types such as limber pine (Pinus flexilis sect and disease leaflet 174. USDA Forest Ser- vice, Washington, DC. US Geological Survey. 2005. Digital representa- James) or bristlecone pine (Pinus aristata MCCAMBRIDGE, W.F. 1974. Pinyon needle scale. tions of tree species range maps from “Atlas of Engelm.) it may be difficult to detect trends Forest insect and disease leaflet 148. USDA For- United States trees,” by Elbert L. Little Jr. (and because of the relatively small numbers of est Service, Washington, DC. other publications). Online at esp.cr.usgs.gov/ FIA plots that occur in those types. MCPHEE, J., A. COMRIE, AND G. GARFIN. 2004. data/atlas/little; last accessed Aug. 30, 2005. The FIA annual inventory system is Drought and climate in Arizona: Top ten ques- providing the intended benefits of shorter tions and answers. University of Arizona Cli- John D. Shaw ([email protected]) is analyst, mate Assessment Project for the Southwest USDA Forest Service, Rocky Mountain Re- reporting cycles and fine-resolution tempo- (CLIMAS), Tucson, AZ. 22 p. ral trends in the states where it has been im- NATIONAL CLIMATIC DATA CENTER. 1994. Time search Station, 507 25th Street, Ogden, UT plemented. It is also providing a valuable bias corrected divisional temperature-precipita- 84401. Brytten E. Steed ([email protected]) is record of change during an ecosystemwide tion-drought index. Documentation for dataset forest entomologist, USDA Forest Health Pro- phenomenon. With full implementation TD-9640. Available from DBMB, NCDC, tection, Ogden Field Office, 4746 S 1900 E, (i.e., all states under annual inventory) and NOAA, Federal Building, 37 Battery Park Av- Ogden, UT 84401. Larry T. DeBlander enue, Asheville, NC 28801–2733. 12 p. the addition of new data every year, the re- NEGRON, J.F., AND J.L. WILSON. 2003. Attributes ([email protected]) is analyst, USDA For- sulting information will become increas- associated with probability of infestation by est Service, Rocky Mountain Research Station, ingly valuable with time and will continue to the pinõn ips, Ips confusus (Coleoptera: Sco- 507 25th Street, Ogden, UT 84401.

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